Continuous miner center drum with offset split surfaces

ABSTRACT

A pair of semi-cylindrical segments adapted to be connected to form a center drum of a cutter head of a mining machine. The split line between the semi-cylindrical segments is not continuous, but lies on more than one plane.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of co-pending U.S. patent applicationSer. No. 12/542,206, now U.S. Pat. No. 8,628,147, filed Aug. 17, 2009,the entire contents of which are hereby incorporated by reference.

BACKGROUND

This disclosure relates to an apparatus for the cutting of earthformations and, more particularly, to drum-type cutters on miningmachines.

Machines for cutting earth formations such as coal and other mineraldeposits, rocky soil, etc., often employ rotary cutters comprisingcylindrical cutter drums which carry pointed cutter bits. Thecylindrical drums are connected to a rotary drive shaft that rotates thedrums at the same time that the cutter is advanced against an earthformation to cut there through.

In some mining machines, for example, carrier arms extend forwardly froma vehicle body and carry a rotary cutter mechanism that rotates about atransverse horizontal axis. The cutter mechanism comprises a supporthousing and a drive shaft assembly rotatably mounted within the housing,and a series of longitudinally spaced cutter drums connected to thedrive shaft assembly to be rotatably driven thereby.

Some of the cutter drums (outside drums) are located to the outside ofthe carrier arms and comprise one-piece cylinders that can be slidaxially over the housing and suitably fastened in place. Others of thedrums (inside drums) are located between the carrier arms. These insidedrums cannot be conveniently removed in an axial direction and thus areusually formed of semi-cylindrical segments that can be separatedradially to provide access to the support housing and drive shaftassemblies for maintenance. Such a mining machine is illustrated in U.S.Pat. No. 4,190,296, which includes a plurality of cutter drums connectedto a drive shaft assembly, the cutter drums including a first pair ofcutter drums located longitudinally outwardly of a pair of arms, and asecond pair of drums located between the arms, each of the second drumscomprising a pair of semi-cylindrical segments.

More particularly, the center drum two halves are bolted together duringinstallation on the machine's cutter head shaft. There is therefore aseam, commonly called a “split line”, at the interface between the twohalves. Generally, the interface between the two halves all lies withina single plane.

An array of bit holders is welded to both halves of the drum. The axialand angular position of the bit holders is carefully selected to providedesired cutting characteristics. A welding fixture is used to providethe precise locating of the bit holders.

In some cases, the desired location of a bit holder falls on the splitline (seam) in the drum. When this happens, the usual solution has beento locate the bit holder as close as possible to the desired location,while avoiding the split line. This compromised bit holder location willoften result in rough cutting and failure of bits, bit holders, anddrive components. Another solution, rarely used, is to weld the bitholder in the preferred location, even though that means welding itacross the split line. Welding across the split line is undesirablebecause it must be done at machine assembly time or even underground,without the benefit of the fixture for precise positioning. Theoverlapping bit holder also makes later drum removal difficult. Further,the welding of a bit holder on a split line may not be as robust as afully supported holder since the mating surfaces do not fit upperfectly.

There therefore exists a need for a continuous miner center drum inwhich all the bit holders can be placed in the optimum locations.

SUMMARY

This invention provides a continuous miner with a center drum in whichthe interface between the two halves falls in multiple planes. Atcertain axial locations along the drum, the interface will be stepped oroffset, so as to fall clear of any bit holders in that location.

This invention will allow for smoother-cutting continuous miners byavoiding compromises in the bit pattern necessitated by the split linein the center drum.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a top view of a continuous miner.

FIG. 2 is a side view of the continuous miner shown in FIG. 1.

FIG. 3 is a side view of a center drum of a cutter head of a continuousminer, with a split line 14 offset in four discreet planes, with thecutter bits on the right end of the drum.

FIG. 4 is a side view of a center drum of a cutter head of a continuousminer, with a split line 14 offset in four discreet planes, with thecutter bits on the left end of the drum.

FIG. 5 is a side view of a center drum shell half with an offset splitline.

FIG. 6 is a side view of a drum shell half in which there is no extrastep at the axial center.

Before one embodiment of the invention is explained in detail, it is tobe understood that the invention is not limited in its application tothe details of the construction and the arrangements of components setforth in the following description or illustrated in the drawings. Theinvention is capable of other embodiments and of being practiced orbeing carried out in various ways. Also, it is to be understood that thephraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. Use of “including”and “comprising” and variations thereof as used herein is meant toencompass the items listed thereafter and equivalents thereof as well asadditional items. Use of “consisting of” and variations thereof as usedherein is meant to encompass only the items listed thereafter andequivalents thereof Further, it is to be understood that such terms as“forward”, “rearward”, “left”, “right”, “upward” and “downward”, etc.,are words of convenience and are not to be construed as limiting terms.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

A preferred embodiment is discussed in conjunction with a mining machine10, as shown in FIGS. 1 and 2. The mining machine 10 comprises aself-propelled vehicle body 2. A longitudinal conveyor (not shown) onthe vehicle body 2 functions to transfer excavated materials from afront end of the vehicle body 2 to a rear discharge end thereof via aconveyor 4. Extending forwardly of the vehicle body 2 is a pair ofsupport arms 6 which support a rotary cutter assembly 8 extending acrossthe front end of the vehicle body. The cutter assembly 8 includes adrum-type cutter mechanism 9 at each end of the cutter assembly 8,separated by a center drum 5. A plurality of cutter bit assemblies 7 arecarried in a helical pattern on the outside surface of the cutterassembly 8.

The continuous mining cutting center drum 5 shown in FIG. 3 depicts asplit line 14 offset in four discreet planes. Each bit 18 is mounted toa bit holder 22, which in turn is welded at base 26 to a cylindricaldrum 30 avoiding all distinct planes which define the split line 14. Theaxial center 34 represents the more typical split line that lies in asingle plane.

In FIG. 4, the apposing view of the cutting drum 10 depicts a commonplacement of a bit holder 22 overlapping the axial center 34,illustrating the compromised location of the posed bit holder 22 bypresent product's configuration.

In the preferred embodiment the two halves of the cylindrical drum 30are identical before the bit holders 22 are welded to them.

It is sometimes desired to angularly offset the bit pattern on one sideof the axial center 34 of the cylindrical drum 30 relative to the otherside, so that no two bits 18 strike the coal at the same time, resultingin smoother cutting. While no bit holders are shown on the left side asin FIG. 3, they would be positioned in angular positions between the bitholders on the right side, as viewed lengthwise along the axial center34.

FIG. 5, illustrates a drum shell half 38 with offset split line. Thisdrum shell half 38 incorporates the extra step 42 in the split line 14to allow the angular offset in the bit pattern as described in thepreceding paragraph. The shaded plane 46 shows where the typicalsingle-plane interface would be.

It should also be noted that in FIG. 5, the mating surfaces that make upthe interface between the two drum shell halves are all parallel to eachother.

FIG. 6 shows a drum shell half 50 in which there is no extra step at theaxial center. This drum shell half 50 would be for a bit lacing patternin which there is no angular offset in the bit pattern between the leftand right sides 54, 58. In other words, the bit pattern on the rightside 58 is a mirror image of the bit pattern on the left side 54.

In FIG. 6, the surfaces that make up the interface between the twohalves of the drum shell are not parallel to each other, but angled.

Various other features and advantages of the disclosure are apparentfrom the following claims.

1. A mining machine comprising: a vehicle body; a pair of arms extendingforwardly from said vehicle body; and a cutter assembly supported by thepair of arms and including a drum and a plurality of cutting bitscoupled to the drum, the drum defining a longitudinal axis and a centralplane intersecting the longitudinal axis, the drum including a firstshell portion having a first mating surface and a second mating surfaceoffset from the first mating surface by a step extending in a planesubstantially perpendicular to the longitudinal axis, and a second shellportion identical to the first shell portion and removably coupled tothe first shell portion to form a substantially cylindrical drum, thesecond shell portion having a third mating surface and a fourth matingsurface offset from the third mating surface by the step, wherein thethird mating surface abuts the first mating surface along a first splitline offset from the central plane, and the fourth mating surface abutsthe second mating surface along a second split line parallel to thefirst split line.
 2. The mining machine of claim 1, wherein the firstshell portion includes a fifth mating surface offset from the secondmating surface by a second step extending in a plane substantiallyperpendicular to the longitudinal axis, and wherein the second shellportion includes a sixth mating surface offset from the fourth matingsurface by the second step, the sixth mating surface abutting the fifthmating surface along a third split line parallel to the second splitline.
 3. The mining machine of claim 2, wherein the first shell portionincludes a seventh mating surface offset from the fifth mating surfaceby a third step extending in a plane substantially perpendicular to thelongitudinal axis, and wherein the second shell portion includes aneighth mating surface offset from the sixth mating surface by the thirdstep, the eighth mating surface abutting the seventh mating surfacealong a fourth split line parallel to the third split line.
 4. Themining machine of claim 1, wherein each of cutter bit is supported by abit holder rigidly coupled to an outer surface of the drum, wherein thebit holders are arranged in a helical pattern extending along thelongitudinal axis, wherein none of the bit holders overlap the firstsplit line or the second split line.
 5. The mining machine of claim 1,wherein the cutting drum is positioned between the pair of arms.
 6. Themining machine of claim 1, wherein the first mating surface and thesecond mating surface are parallel to each other.
 7. The mining machineof claim 1, wherein the first mating surface and the second matingsurface are not parallel to each other.
 8. A mining machine comprising:a vehicle body; a pair of arms extending forwardly from said vehiclebody; and a cutter assembly mounted on the pair of arms and including adrum cutter, the drum cutter including a first drum shell half and asecond drum shell half coupled to the first drum shell half to form asubstantially cylindrical drum, the drum cutter defining a longitudinalaxis and a central plane intersecting the longitudinal axis, a splitline being defined where the first drum shell half mates with the seconddrum shell half, the split line defining a first mating interface offsetfrom and parallel to the central plane and a second mating interfaceoffset from and parallel to the first mating interface, the first matinginterface and the second mating interface being offset by a step,wherein the first drum shell half and the second drum shell half areidentical.
 9. The mining machine of claim 8, wherein the step is a firststep extending substantially perpendicular to the central plane, andwherein the split line further defines a third mating interface offsetfrom the second mating interface by a second step extendingsubstantially perpendicular to the central plane.
 10. The mining machineof claim 9, wherein the split line further defines a fourth matinginterface offset from and parallel to the third mating interface, thethird mating interface and the fourth mating interface being offset by asecond step extending substantially perpendicular to the central plane.11. The mining machine of claim 8, wherein the cutter assembly furtherincludes a plurality of cutter bits coupled to an outside surface of thedrum cutter in a helical pattern extending along the longitudinal axis,wherein each cutter bit is supported on a bit holder rigidly coupled tothe outside surface of the drum cutter and not overlapping the splitline.
 12. The mining machine of claim 8, wherein the cutter assemblyfurther includes a plurality of cutter bits coupled to an outsidesurface of the drum cutter in a continuous helical pattern extendingalong the longitudinal axis, wherein no two cutter bits are angularlyaligned along the longitudinal axis such that when the cutter assemblyrotates, no two cutting bits contact a surface at substantially the sametime.
 13. The mining machine of claim 8, wherein the cutter assemblyfurther includes a first drum cutter mechanism positioned outside thepair of arms to a first side and a second drum cutter mechanismpositioned outside the pair of arms to a second side, and wherein thedrum cutter is positioned between the pair of arms.
 14. The miningmachine of claim 8, wherein the first mating interface defines a firstmating surface between the first drum shell half and the second drumshell half, and wherein the second mating interface defines a secondmating surface between the first drum shell half and the second drumshell half, the first mating surface and the second mating surface beingparallel to each other.
 15. The mining machine of claim 8, wherein thefirst mating interface defines a first mating surface between the firstdrum shell half and the second drum shell half, and wherein the secondmating interface defines a second mating surface between the first drumshell half and the second drum shell half, the first mating surface andthe second mating surface not being parallel to each other.
 16. A cutterassembly for a continuous mining machine, the cutter assemblycomprising: a cylindrical drum defining a longitudinal axis and acentral plane intersecting the longitudinal axis, the drum including afirst shell portion having a first mating surface, a second matingsurface offset from the first mating surface by a first step extendingin a plane substantially perpendicular to the longitudinal axis, and athird mating surface offset from the second mating surface by a secondstep extending in a plane substantially perpendicular to thelongitudinal axis, and a second shell portion removably coupled to thefirst shell portion and substantially identical to the first shellportion, the second shell portion having a fourth mating surface, afifth mating surface offset from the third mating surface by the firststep, and a sixth mating surface offset from the fifth mating surface bythe second step, the fourth mating surface abutting the first matingsurface along a first split line, the fifth mating surface abutting thesecond mating surface along a second split line, and the sixth matingsurface abutting the third mating surface along a third split line; anda plurality of cutting bits coupled to the drum, each cutting bitsupported in a bit holder rigidly coupled to an outer surface of thecylindrical drum and arranged in a helical pattern such that none of thebit holders overlap the first, second, or third split lines.
 17. Thecutter assembly of claim 16, wherein none of the first mating surface,the second mating surface, and the third mating surface is on the sameplane.
 18. The cutter assembly of claim 16, wherein the first matingsurface, the second mating surface, and the third mating surface areparallel to each other.
 19. The cutter assembly of claim 16, wherein atleast one of the first mating surface, the second mating surface, andthe third mating surface is not parallel to the other mating surfaces.20. The cutter assembly of claim 16, wherein the first shell portionincludes a seventh mating surface offset from the third mating surfaceby a third step extending in a plane substantially perpendicular to thelongitudinal axis, and wherein the second shell portion includes aneighth mating surface offset from the sixth mating surface by the thirdstep, the eighth mating surface abutting the seventh mating surfacealong a fourth split line parallel to the third split line.